metallothionein and bismuth-nitrate

In order to elucidate the role of metallothionein (MT) in preventing the adverse effects of X-ray irradiation, we examined the susceptibility of MT-I/II null mice to bone marrow injury caused by X-irradiation and effects of pretreatment with MT-inducing metals on X-ray injury. Eight-week-old male mice were exposed to a single bout of whole-body X-irradiation at a dose between 0.1 and 6.0 Gy. The numbers of leukocytes, reticulocytes with micronuclei (MNRET) in the blood, and polychromatic erythrocytes with micronuclei (MNPCE) in the bone marrow were determined 24 hr after X-irradiation. X-irradiation significantly decreased the total number of leukocytes in MT-I/II null mice and wild-type mice in a dose-dependent manner, but the total number of leukocytes was significantly lower in MT-I/II null mice than in wild-type mice at a low dose of irradiation, between 0.1 and 1.0 Gy. X-irradiation (0.1 and 0.5 Gy) significantly increased the appearance of MNRET and MNPCE in both strains, but the increase was greater in the MT-I/II null mice than in the wild-type mice. Additional groups of mice were pre-administered bismuth nitrate or zinc sulfate to induce MT in the bone marrow cells prior to X-irradiation; the X-ray injury was prevented by such treatments in wild-type mice only. Thus, the present results suggest that MT plays a protective role against a low dose of X-ray injury.

Topics: Animals; Bismuth; Bone Marrow; Dose-Response Relationship, Radiation; Erythrocytes; Leukocytes; Male; Metallothionein; Mice; Mice, Knockout; Micronuclei, Chromosome-Defective; Nitrates; Reticulocytes; Whole-Body Irradiation; X-Rays; Zinc Sulfate

The effects of bismuth nitrate (BN) on the lethal effect of and injury to bone marrow by gamma-irradiation were examined. Mice were given daily s.c. injections of BN for 2 days and were exposed to whole-body irradiation (137Cs; 8 grays) 24 hr after the second injection of BN. All mice exposed to gamma-irradiation without treatment with BN died within 30 days, but the lethal effect of gamma-irradiation was markedly reduced in mice given BN before irradiation. Irradiation (3 grays) significantly reduced the total number of leukocytes 1 day after irradiation but the number of leukocytes subsequently increased in both nontreated and BN-treated irradiated mice. However, the rate of recovery of the total number of leukocytes, as monitored from 5 days after irradiation, was significantly higher in BN-treated mice than in the nontreated mice. Reductions in the viability of hematopoietic stem cells (determined by monitoring the number of colony-forming units in the spleen) that were induced by gamma-irradiation (3 grays) were considerably diminished by the treatment of mice with BN before irradiation. BN significantly increased the concentration of metallothionein in the bone marrow cells of mice, but levels of other cellular antioxidants, such as catalase, superoxide dismutase, glutathione-S-transferase, glutathione peroxidase and glutathione, were unchanged. These results suggest that BN protects bone marrow cells against the toxic effects of gamma-irradiation by inducing the synthesis of metallothionein in the bone marrow. Metallothionein might play an important role in determining the sensitivity of animals to gamma-irradiation.

Topics: Animals; Bismuth; Bone Marrow; Gamma Rays; Male; Metallothionein; Mice; Mice, Inbred ICR; Nitrates; Radiation-Protective Agents

The kidney, in particular the proximal convoluted tubule, is a major target site for the toxic effects of various metals. However, little is known about the early effects of these metals after acute exposure in man. In the present study we have evaluated the toxicity of several inorganic metal compounds (CdCl2, HgCl2, ZnCl2, and Bi(NO3)3) and the induction of metallothionein by these compounds in cultured human proximal tubular (HPT) cells for up to 4 days. The results showed that bismuth was not toxic even at the highest dose (100 microM) used, while zinc, cadmium and mercury exhibited varying degrees of toxicity, zinc being the least toxic and mercury the most potent. A significant degree of interindividual variation between the different isolates used in these experiments was also observed. All metals used in the present study induced MT, as revealed by immunocytochemistry. All metals showed maximal induction between 1 and 3 days after treatment. Although a certain amount of constitutive MT was present in the cultures, the intensity of the staining varied with time in culture and between the different isolates studied. No correlation could be made between the intensity of the staining in control cultures (indicating total amount of constitutive MT) and the susceptibility of a given isolate to metal toxicity. Furthermore, no correlation could be made between metal-induced MT and the susceptibility of a given isolate to that particular metal.

Topics: Bismuth; Cadmium Chloride; Cells, Cultured; Chlorides; Dose-Response Relationship, Drug; Humans; Immunohistochemistry; Kidney Tubules, Proximal; Mercuric Chloride; Metallothionein; Nitrates; Zinc Compounds

To elucidate the protective role of metallothionein (MT) in the prevention of cisplatinum (cis-DDP) toxicity, we investigated the lethal and renal toxicities caused by cis-DDP in MT-null transgenic mice in comparison with wild-type control mice, and examined the effect of pretreatment with bismuth nitrate or zinc sulfate on the cis-DDP nephrotoxicity. The MT-null mice were of mixed 129 Ola and C57BL/6 genetic background. Since no differences in cis-DDP nephrotoxicity were observed between these strains, C57BL/6J mice were used as the wild-type control. The basal MT levels in the kidneys were negligible in the MT-null mice and 2.93 +/- 0.77 micrograms/g tissue in the C57BL/6J mice. In terms of both the lethal and renal toxicities of cis-DDP, MT-null mice were far more sensitive than C57BL/6J mice. Preinduction of renal MT synthesis by administration of bismuth nitrate or zinc sulfate protected C57BL/6J mice from cis-DDP nephrotoxicity. In the case of MT-null mice, however, renal MT could not be induced by pretreatment with these metal compounds, and renal toxicity of cis-DDP was not prevented by this pretreatment. These results suggest that MT is an important factor with the potential to suppress the development of cis-DDP toxicity.

Topics: Animals; Antineoplastic Agents; Bismuth; Blood Urea Nitrogen; Cisplatin; Creatinine; Female; Injections, Intraperitoneal; Kidney; Kidney Diseases; Metallothionein; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Nitrates; Sulfhydryl Compounds; Zinc Sulfate

The clastogenic effects of chromium compounds (CrCl3 and K2CrO4) and selenium compounds (H2SeO3 and Na2SeO4) in mouse bone marrow cells have been investigated. K2CrO4 induced significant, dose-related increases in micronuclei. H2SeO3 also showed a significant micronucleus induction at the highest dose. CrCl3 and Na2SeO4 were negative for micronuclei induction in mice. The suppressive effect of Bi(NO3)3, a metallothionein inducer, on the micronucleus induction by K2CrO4 and H2SeO3 has been also investigated. Pretreatment with Bi(NO3)3 suppressed the micronucleus induction by K2CrO4 and H2SeO3. In addition, the incidence of micronucleus induction seemed to be reduced by double dosing with K2CrO4 and H2SeO3, compared to single dosing. It is generally recognized that a number of metal compounds induce metallothionein synthesis. These results suggest that the mechanism of suppression of micronucleus induction by K2CrO4 and H2SeO3 involve possible participation of metallothionein in mouse bone marrow.

Topics: Animals; Bismuth; Chromium Compounds; Erythrocytes; Male; Metallothionein; Mice; Mice, Inbred Strains; Micronuclei, Chromosome-Defective; Micronucleus Tests; Mutagens; Nitrates; Selenium Compounds

Topics: Adenine; Animals; Aorta; Bismuth; Cadmium; Cattle; Cells, Cultured; Drug Interactions; Endothelium, Vascular; Isotope Labeling; Metallothionein; Nitrates; Spectrophotometry, Atomic; Tritium

The effect of pretreatment with metallothionein (MT) inducers (bismuth nitrate or zinc chloride) on clastogenicity of anticancer drugs was investigated. Bismuth nitrate (50 mumol/kg) or zinc chloride (400 mumol/kg) was administered s.c. to mice once a day for two days prior to treatment with 3.3 mumol/kg of cis-diamminedichloroplatinum(II) (cis-DDP), 3.4 mumol/kg of adriamycin (ADR), 72 mumol/kg of cyclophosphamide (CPA) or 0.41 mumol/kg of L-phenylalanine mustard (L-PAM). The frequency of occurrence of erythrocytes with micronuclei in bone marrow was increased by each anticancer drug at 24 h after treatment. Micronucleus formation was significantly prevented by pretreatment with either bismuth nitrate or zinc chloride. MT concentration in bone marrow cells of mice at the time of treatment with anticancer drugs increased to 2- and 3.5-fold by pretreatment with bismuth nitrate and zinc chloride, respectively. These results indicate that MT induction in bone marrow cells effectively prevents micronucleus induction of anticancer drugs.

Topics: Animals; Antineoplastic Agents; Bismuth; Bone Marrow; Chlorides; Cisplatin; Cyclophosphamide; Doxorubicin; Male; Melphalan; Metallothionein; Mice; Mice, Inbred ICR; Micronucleus Tests; Mutagens; Nitrates; Zinc Compounds

Metallothionein synthesis induced by bismuth nitrate was characterized using a cell culture system. It was found that bismuth (1-10 microM) significantly increased the intracellular accumulation of metallothionein in bovine aortic endothelial cells without an exhibition of cytotoxicity and a change of either general protein synthesis or proliferative DNA synthesis after a 24-h incubation. A low increase in the metallothionein accumulation was observed in bovine aortic smooth muscle cells; however, porcine kidney epithelial LLC-PK1 cells, human Chang liver cells and two human hepatoma cell lines (HLF cells and Hep-G2 cells) did not respond to bismuth. Other cations including cobalt, lead and zinc at 10 microM failed to induce metallothionein in endothelial cells, although cadmium at 1 microM was a strong inducer. Bismuth accumulated highly in endothelial cells but very slightly in LLC-PK1 cells and Chang liver cells. The present data suggest that bismuth is a selective inducer of metallothionein of vascular endothelial cells and this cell type particularly responds to the cation.

Topics: Adenine; Animals; Bismuth; Carcinoma, Hepatocellular; Cattle; Cells, Cultured; Endothelium, Vascular; Kidney; Leucine; Liver; Metallothionein; Metals; Muscle, Smooth, Vascular; Nitrates; Thymidine

To determine whether Hg accumulated in renal cells is secreted into the lumen of proximal tubules with intracellular glutathione (GSH) and reabsorbed by tubular cells via a gamma-glutamyltranspeptidase (gamma-GTP)-dependent process as in the case of GSH itself, the effect of postadministration of acivicin (1 mmol/kg i.p.), a gamma-GTP inhibitor, on renal Hg accumulation was investigated in mice. Renal Hg content 4 hr after injection of CH3HgCl or HgCl2 (5 mumol/kg i.v.) was decreased to 35 or 44% of control, respectively, but urinary Hg excretion was increased by acivicin administration 2 hr after injection of the mercurials. When renal GSH was decreased to 19% of control by treatment with DL-buthionine-S,R-sulfoximine (4 mmol/kg s.c.) 2 hr before acivicin injection, the increase in urinary Hg excretion caused by acivicin was suppressed. Acivicin administration 24 hr after injection of the mercurials decreased renal methylmercury content determined 2 hr after acivicin injection and increased urinary Hg excretion. The postadministration of acivicin, however, did not affect the renal content of inorganic Hg which predominantly bound to metallothionein (MT) induced by HgCl2 itself. Pretreatment with Bi(NO3)3 as a renal MT inducer diminished the effect of acivicin administered 2 hr after HgCl2 injection on renal Hg content and urinary excretion. These results suggest that methylmercury and inorganic Hg bound to ligands other than MT in renal cytosol may be secreted into the lumen of proximal tubules with intracellular GSH and be reabsorbed via a gamma-GTP-dependent process.

Topics: Absorption; Animals; Bismuth; gamma-Glutamyltransferase; Glutathione; Isoxazoles; Kidney Tubules; Male; Mercury; Metallothionein; Mice; Mice, Inbred ICR; Nitrates

We examined the efficacy of metallothionein induction in the prevention of the carcinogenic action of cis-platinum and melphalan administered repeatedly to mice over a relatively long period. The increased pulmonary metallothionein induced by bismuth or zinc compounds during the period of chemotherapy with cis-platinum or melphalan protected the mice from carcinogenesis of these drugs in the lung. These results suggested the efficacy of metallothionein inducers in suppression of carcinogenicity considered as a secondary effect of anticancer agents in cancer chemotherapy.

Topics: Animals; Anticarcinogenic Agents; Bismuth; Carcinogens; Chlorides; Cisplatin; Female; Lung; Lung Neoplasms; Melphalan; Metallothionein; Mice; Mice, Inbred A; Nitrates; Zinc Compounds

The effects of bismuth nitrate pretreatment on the toxicity and antitumor activity of cis-diamminedichloroplatinum (cisplatin, CDDP) were examined in nude mice that had been inoculated with human bladder-tumor tissue. Pretreatment with bismuth nitrate depressed the renal toxicity of CDDP without compromising its activity against a transplantable human bladder tumor. Renal metallothionein (MT) and bismuth (Bi) levels in nude mice were markedly increased by Bi preadministration, but no significant MT induction was observed in inoculated human bladder-tumor tissue in which only a trace amount of Bi was incorporated. Furthermore, it was confirmed that tumor platinum (Pt) concentrations in CDDP-treated mice were not affected by Bi pretreatment. Thus, the administration of Bi compounds prior to chemotherapy with CDDP may provide an effective mode of treatment for advanced bladder tumors.

Topics: Animals; Bismuth; Cisplatin; Drug Evaluation, Preclinical; Drug Interactions; Drug Therapy, Combination; Humans; Kidney; Male; Metallothionein; Mice; Mice, Nude; Neoplasm Transplantation; Nitrates; Premedication; Urinary Bladder Neoplasms

Metallothionein functions as a radical scavenger protecting cells from the indirect effect of radiations. We investigated the effect of bismuth nitrate, an efficient inducer of metallothionein, on acute and late effects of radiation in mice. Metallothionein contents were examined in several organs after the administration of bismuth nitrate. The content in bone marrow increased 2-fold in the treated as compared to the control mice. This treatment protected irradiated mice from bone marrow death and increased the number of endogenous spleen colonies. The metallothionein content in the ileum did not change after treatment with bismuth nitrate. Mice were not protected by bismuth nitrate when exposed to 9 Gy of X-rays. This suggests that this agent does not protect from gastrointestinal death. The incidence of X-ray-induced thymic lymphomas was lowered by the administration of bismuth nitrate in mice exposed to four fractionated doses of 1.3 Gy of X-rays. These results indicate that bismuth nitrate effectively modified both acute and late effects of X-rays by inducing metallothionein in the target tissues.

Topics: Animals; Bismuth; Metallothionein; Mice; Mice, Inbred C57BL; Neoplasms, Radiation-Induced; Nitrates; Radiation-Protective Agents; Thymoma; Thymus Neoplasms